Organic proton-type ionic liquid, two-dimensional perovskite pure-phase quantum well film, preparation method and use thereof

ABSTRACT

Disclosed are an organic proton-type ionic liquid, a film with a two-dimensional perovskite pure-phase quantum well structure, a preparation method and use thereof. The chemical formula of the organic proton-type alkylamine acetate ionic liquid is RNH 3   + —RCOO − , where R represents an alkyl group of C4-8 or a phenyl group, preferably, the chemical formula of the organic proton-type alkylamine acetate ionic liquid is CH 3 (CH 2 ) 3 NH 3   + —CH 2 COO − . The organic proton-type alkylamino acetate ionic liquid disclosed in the present disclosure can be used to prepare perovskite material, the prepared perovskite film thereby can form a pure-phase single quantum well, and the crystal grain size of the film can reach the level of micrometers or even millimeters.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a 371 of International Application No.PCT/CN2021/114258, filed Aug. 24, 2021, which claims priority to and thebenefit of Chinese Patent Application No. 202010863816.2, filed Aug. 25,2020, the contents of which are incorporated by reference herein intheir entirety.

TECHNICAL FIELD

The present disclosure relates to the field of organic and inorganicphotoelectronic devices, in particular to an organic proton-typebutylamine acetate ionic liquid, a film with a two-dimensionalperovskite pure-phase quantum well structure, a preparation method anduse thereof.

BACKGROUND

The existing low-dimensional perovskite materials are prepared by usingthe hydriodate and the hydrobromate of amine compounds as organic aminesalts. The low-dimensional perovskite prepared by the existing materialsand methods has a multi-phase mixed multi-quantum well structure, and asingle pure-phase perovskite quantum well has not been obtained,especially a perovskite film with a higher quantum well widthdistribution.

SUMMARY

The objective of the present disclosure is to provide an organicproton-type alkylamine acetate ionic liquid, which can be used toprepare perovskite material.

Furthermore, the present disclosure also provides a method for preparingthe above organic proton-type alkylamine acetate ionic liquid.

Furthermore, the present disclosure also provides a method for preparinga film with a two-dimensional perovskite pure-phase quantum wellstructure based on the organic proton-type alkylamine acetate ionicliquid.

Furthermore, the present disclosure also provides a use of the aboveorganic proton-type alkylamine acetate ionic liquid.

The organic proton-type alkylamine acetate ionic liquid can be used as anew solvent for dissolving the perovskite precursor.

The organic proton-type butylamine acetate ionic liquid can be used as apotential electrolyte for lithium ion batteries.

The present disclosure provides an organic proton-type alkylamineacetate ionic liquid, wherein a chemical formula of the organicproton-type alkylamine acetate ionic liquid is RNH₃ ⁺—RCOO⁻, and Rrepresents an alkyl group of C4-8 or a phenyl group.

In some embodiments, the organic proton-type alkylamine acetate ionicliquid is a butylamine acetate ionic liquid, and the chemical formula ofthe butylamine acetate ionic liquid is CH₃(CH₂)₃NH₃ ⁺—CH₂COO⁻.

The present disclosure provides a method for preparing the organicproton-type alkylamine acetate ionic liquid described above, comprising:

-   -   1) mixing a carboxyl group-containing organic acid and an amine        group-containing organic amine in a molar ratio of the amine        group and the carboxyl group of 1:1, then adding the same volume        of a diluent as the amine group-containing organic amine,        cooling to 0° C. and stirring to react for 2-2.5 h to obtain a        mixture; and    -   2) removing the diluent and other organic impurities from the        mixture by reduced pressure distillation at 80° C., then        lowering the temperature to −4° C. for recrystallization,        standing for 1 h to obtain a solidified mixture, washing the        solidified mixture with 1000 mL of a volatile anti-solvent for 3        times, then dissolving the solidified mixture in 100 mL of a        diluent, stirring for 30 min, and then removing the diluent by        reduced pressure distillation at 80° C. to obtain the organic        proton-type alkylamine acetate ionic liquid.

In some embodiments, the carboxyl group-containing organic acid includesone or more of formic acid, acetic acid, propionic acid, butyric acid,pentanoic acid and hexanoic acid;

-   -   the amino group-containing organic amine is one or more selected        from aminomethane, (di)aminoethane, (di)aminopropane,        (di)aminobutane, (di)aminopentane and (di)aminohexane;    -   the diluent is one or more selected from water, ethanol,        methanol, propanol and isopropanol; and    -   the volatile anti-solvent is an ethers reagent.

In some embodiments, the ethers reagent is diethyl ether.

The present disclosure provides a use of the organic proton-typealkylamine acetate ionic liquid described above in the fields of organicand inorganic photoelectric materials and semiconductor devices.

The present disclosure provides a use of the organic proton-typealkylamine acetate ionic liquid described above in the fields of newsolvents for dissolving perovskite precursors and electrolytes forlithium-ion batteries.

The present disclosure provides a two-dimensional perovskite pure-phasequantum well material prepared based on an organic proton-typealkylamine acetate ionic liquid, wherein the chemical formula of thetwo-dimensional perovskite pure-phase quantum well material isA_(a)B_(b)M_(m)X_(x), where A is a long carbon chain organic cation, anda-value ranges from 0 to 2.5;

-   -   B is an amine group-containing monovalent cation, b-value        satisfies 0≤(m−1)<b<(m+1), and m is any natural number; M is a        divalent metal cation; and    -   X is one or more of halogen ion, carboxylate ion and thiocyanate        ion, and x-value satisfies (3m−1)<x<(3m+1).    -   In some embodiments, the long carbon chain organic cation is one        or more of CH₃CH₂NH₃ ⁺, CH₃CH₂CH₂NH₃ ⁺, CH₃CH₃CH₂CH₂NH₃ ⁺,        CH₃CH₂CH₂CH₂CH₂NH₃ ⁺ and CH₃CH₂CH₂CH₂CH₂CH₂NH₃ ⁺;    -   the amine group-containing monovalent cation is one or more of        methylamine ion, formamidine ion, guanidine ion, and cesium ion;        the divalent metal cation is one or more of lead ion, tin ion,        copper ion, zinc ion, manganese ion and bismuth ion; and    -   the halogen is one or more of F, Cl, Br, and I.

In some embodiments, the chemical formula of the two-dimensionalperovskite pure-phase quantum well material is A₂B₂M₃X₁₀.

In some embodiments, the chemical formula of the two-dimensionalperovskite pure-phase quantum well material is[CH₃(CH₂)₃NH₃]₂(CH₃NH₃)Pb₂I₇, [CH₃(CH₂)₃NH₃]₂(CH₃NH₃)₂Pb₃I₁₀,[CH₃(CH₂)₃NH₃]₂(CH₃NH₃)₃Pb₄I₁₃ or [CH₃(CH₂)₃NH₃]₂(CH₃NH₃)₄M₅I₁₆.

The present disclosure provides a method for preparing a film with atwo-dimensional perovskite pure-phase quantum well structure,comprising:

-   -   1) preparing materials in a molar ratio of the organic        proton-type alkylamine acetate ionic liquid, BX and MX of        2:(m+1):m;    -   2) adding BX to a DMSO solution to prepare a DMSO mixture with a        BX mass fraction of 1-35%;    -   3) adding the organic proton-type alkylamine acetate ionic        liquid to the DMSO mixture prepared in step 2), mixing evenly,        stirring at 25° C. for 2 h, and then adding MX;    -   4) then adding 1600 μL of DMF reagent, heating to 65° C. and        stirring until fully dissolved, and cooling to room temperature        to obtain a mixed solution;    -   5) subjecting the mixed solution prepared in step 4) to        spin-coating with heating on the surface of a glass substrate in        the air with a humidity of 20%-80%, and maintaining the        temperature at 25° C.-250° C. to obtain the two-dimensional        perovskite pure-phase quantum well film;    -   where, X is one or more of halogen ion, carboxylate ion and        thiocyanate ion;    -   BX is a compound salt of a monovalent cation; and    -   MX is a compound formed by a divalent metal cation and an X ion.

In some embodiments, a compound salt of the monovalent cation is one ormore selected from a compound salt of methylamine ion, a compound saltof formamidine ion, a compound salt of guanidine ion and a compound saltof cesium ion.

In some embodiments, an addition amount of the DMF reagent in the step3) is 5-50 times an addition amount of the organic proton-typealkylamine acetate ionic liquid in volume.

In some embodiments, the spin-coating with heating comprises:

-   -   heating the glass substrate to 80° C.-100° C., setting a        spin-coating speed to 500-1000 rpm/min and performing        spin-coating for 5-10 s, then setting a spin-coating speed to        2000-6000 rpm/min and performing spin-coating for 5-10 s,        continuously heating the substrate between the two spin-coating        steps, covering a film obtained after spin-coating with a petri        dish with a diameter of 100 mm, and then subjecting to        heat-treatment at 80° C.-120° C. for 5-10 min.

In some embodiments, the method for preparing a film with atwo-dimensional perovskite pure-phase quantum well structure comprises:

-   -   1) preparing materials in a molar ratio of butylamine acetate        ionic liquid, methyl ammonium iodide and lead iodide of 2:4:3;    -   2) adding methyl ammonium iodide to the DMSO solution to prepare        a DMSO mixture with a mass fraction of methyl ammonium iodide of        1-35 wt %;    -   3) adding butylamine acetic acid ionic liquid to the DMSO        mixture prepared in step 2), mixing evenly, stirring at 25° C.        for 2 h, and then adding lead iodide powder; then adding a DMF        reagent, heating to 65° C., stirring until fully dissolved, and        cooling to room temperature to obtain a mixed solution; and    -   4) subjecting the mixed solution prepared in step 3) to        spin-coating with heating on the surface of the glass substrate        in the air with a humidity of 20%-80%, and maintaining the        temperature at 25° C.-250° C.

Compared with the above background art, the present disclosure has thefollowing advantages:

-   -   1) New organic butylamine acetate ionic liquid (BAAc,        CH₃(CH₂)₃NH₃+—CH₂COO⁻) is used, which is cheaper and more        readily available than traditional halogen chemicals.    -   2) The prepared perovskite film can form a pure-phase single        quantum well, and the crystal grain size of the film can reach a        level of micrometers or even millimeters.    -   3) The carboxyl group-containing organic amine salts can further        increase the size and width of the single quantum well.

The low-dimensional perovskite materials prepared in the presentdisclosure is an ionic liquid molten salt formed based on thecarboxylate of an organic amine compound. It is a new type of liquid,stable, inexpensive, and easily available organic amine salt, which canbe used as a solvent to directly prepare perovskite materials.

The low-dimensional perovskite prepared by the existing materials andmethods has a multi-phase mixed multi-quantum well structure, and thepresent disclosure provides a pure-phase quantum well structure, whichis a major breakthrough in this field. Compared with the low-dimensionalperovskite materials prepared by the existing methods and materials, thematerial in the present disclosure has the advantages of similar orsuperior photoelectric conversion efficiency, improved stability of thedevice, low cost, simpler operation, and more suitable for large-areapreparation.

The low-dimensional perovskite material prepared by organic amine ionicliquid is more stable and efficient because of the extra hydrogenbonding and van der Waals force, which makes the inorganic layer andorganic layer combine more strongly.

The prior art has not yet obtained a single pure-phase perovskitequantum well, especially a perovskite film with a higher quantum wellwidth distribution. The two-dimensional perovskite pure-phase quantumwell film prepared by the present disclosure has a purity of the specialwidth quantum well more than 98%.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the appearance of the organic proton-type butylamineacetate ionic liquid.

FIG. 2 is an ultrafast spectroscopic analysis spectrum of thetwo-dimensional perovskite pure-phase quantum well film prepared inExample 1.

FIG. 3 is an ultrafast spectroscopic analysis spectrum of thetwo-dimensional perovskite pure-phase quantum well film prepared inExample 2.

FIG. 4 is an ultrafast spectroscopic analysis spectrum of thetwo-dimensional perovskite pure-phase quantum well film prepared inExample 3.

FIG. 5 is an ultrafast spectroscopic analysis spectrum of thetwo-dimensional perovskite pure-phase quantum well film prepared inExample 4.

FIG. 6 is an ultrafast spectroscopic analysis spectrum of thetwo-dimensional perovskite pure-phase quantum well film prepared inComparative Example 1.

FIG. 7 is an ultrafast spectroscopic analysis spectrum of thetwo-dimensional perovskite pure-phase quantum well film prepared inComparative Example 2.

FIG. 8 is an ultrafast spectroscopic analysis spectrum of thetwo-dimensional perovskite pure-phase quantum well film prepared inComparative Example 3.

FIG. 9 is a scanning electron micrograph of the two-dimensionalperovskite pure-phase quantum well film prepared in Example 1.

FIG. 10 is a scanning electron micrograph of the two-dimensionalperovskite pure-phase quantum well film prepared in Comparative Example1.

FIG. 11 is a nuclear magnetic resonance hydrogen spectrum of theproton-type butylamine acetate ionic liquid.

DETAILED DESCRIPTION

In order to enable those skilled in the art to better understand thetechnical solutions of the present disclosure, the present disclosurewill be further described in detail below with reference to theaccompanying drawings and specific embodiments.

Source of Raw Materials.

Except for the organic amine salt ionic liquid, the materials used inthe embodiments of the present disclosure are all commerciallyavailable, and the purity is higher than 98-99%.

The instruments and equipment used in the present disclosure are asfollows:

-   -   magnetic heating stirrer (1 set), freezing thermostat (1 set),        rotary evaporator (1 set), mechanical pump (1 set), heating        spin-coater (1 set), spin-coater (2 sets), and glove box (1        set).

Preparation of Organic Proton-Type Butylamine Acetate Ionic Liquid:

-   -   1) the acetic acid and 1-aminobutane were mixed in a molar ratio        of 1:1, then the same volume of ethanol as 1-aminobutane was        added, the temperature was cooled to 0° C. and stirred for 2 h        to obtain a mixture; and    -   2) the ethanol and water were removed from the mixture by        reduced pressure distillation at 80° C., then the temperature        was lowered to −4° C. for recrystallization, a solidified        mixture was obtained after standing for 1 h, the mixture was        washed with 1000 mL of diethyl ether for 3 times, then the        mixture was dissolved in 100 mL of ethanol, stirred for 30 min,        and then the ethanol was removed by reduced pressure        distillation at 80° C. to obtain an organic proton-type        butylamine acetate ionic liquid (CH₃(CH₂)₃NH₃ ⁺—CH₂COO⁻).

As shown in the subgraph on the right side of FIG. 1 , the organicproton-type butylamine acetate ionic liquid prepared by the presentdisclosure is a colorless and transparent liquid with good fluidity andspecial aromatic odor, which is a new type of environmentally friendlyand pollution-free organic amine salt for low-dimensional perovskite.The subgraph on the left side of FIG. 1 is a common organic halogenorganic amine salt, which is white powder or massive crystal inappearance.

FIG. 11 is a nuclear magnetic resonance hydrogen spectrum of the organicproton-type butylamine acetate ionic liquid, indicating that the productis an ionic product composed of butylamine and acetate.

Example 1

Preparation of Two-Dimensional Perovskite Pure-Phase Quantum Well Film(m-Value is 2, a Narrow Quantum Well Structure with a Broad Band-Gap):

82.94 mg of butylamine acetate ionic liquid CH₃(CH₂)₃NH₃·CH₂COO⁻ wasdrawn, 148.72 mg of methyl ammonium iodide CH₃NH₃I was weighed, then thetwo were preferentially mixed in 400 μL of DMSO solution, stirred fullyat 25° C. for about 2 h. When the solution was uniform, 287.48 mg ofPbI₂ powder was weighed, and then 1600 μL of DMF reagent was drawn to beadded in the solution to obtain a mixture, the mixture was continued toheat and stir at 65° C. until it was completely dissolved, and finallycooled to room temperature for use. The mixture was subjected to heatingcoating in the air with a humidity of 20%-80%, the glass substrate wasmaintained smooth and tidy during the entire coating process, and thetemperature was maintained at 25° C.-250° C. First, the glass substratewas heated to 80-100° C., the spin-coating speed was set to 500-1000rpm/min, and the spin-coating time was 5-10 s, secondly, thespin-coating speed was set to 2000-6000 rpm/min, the spin-coating timewas 5-10 s, the substrate was heated continuously between the twospin-coating steps. The film obtained after spin-coating was coveredwith a petri dish with a diameter of 100 mm, and then subjected to aheat treatment at 80-120° C. Finally, a flat and smooth two-dimensionalperovskite pure-phase quantum well film with micron-level grains wasobtained, as shown in FIG. 9 , of which the chemical formula is[CH₃(CH₂)₃NH₃]₂(CH₃NH₃)Pb₂I₇. FIG. 10 is a two-dimensional perovskitemultiphase quantum well film prepared by butylamine iodine.

Example 2

Preparation of Two-Dimensional Perovskite Pure-Phase Quantum Well Film:

56.78 mg of butylamine acetate ionic liquid CH₃(CH₂)₃NH₃ ⁺—CH₂COO⁻ wasdrawn, 135.89 mg of methyl ammonium iodide CH₃NH₃I was weighed, then thetwo were preferentially mixed in 400 μL of DMSO solution, stirred fullyat 25° C. for about 2 h. When the solution was uniform, 295.51 mg ofPbI₂ powder was weighed, and then 1600 μL of DMF reagent was drawn to beadded in the solution to obtain a mixture, the mixture was continued toheat and stir at 65° C. until it was completely dissolved, and finallycooled to room temperature for use. The mixture was subjected to heatingcoating in the air with a humidity of 20%-80%, the glass substrate wasmaintained smooth and tidy during the entire coating process, and thetemperature was maintained at 25° C.-250° C. First, the glass substratewas heated to 80-100° C., the spin-coating speed was set to 500-1000rpm/min, and the spin-coating time was 5-10 s, secondly, thespin-coating speed was set to 2000-6000 rpm/min, the spin-coating timewas 5-10 s, the substrate was heated continuously between the twospin-coating steps. The film obtained after spin-coating was coveredwith a petri dish with a diameter of 100 mm, and then subjected to aheat treatment at 80-120° C. Finally, a flat and smooth two-dimensionalperovskite pure-phase quantum well film with micron-level grains wasobtained with a chemical formula of [CH₃(CH₂)₃NH₃]₂(CH₃NH₃)₂Pb₃I₁₀.

Example 3

Preparation of Two-Dimensional Perovskite Pure-Phase Quantum Well Film(m-Value is 4, a Broad Quantum Well Structure with a Narrow Band-Gap):

43.18 mg of butylamine acetate ionic liquid CH₃(CH₂)₃NH₃ ⁺—CH₂COO⁻ wasdrawn, 129.06 mg of methyl ammonium iodide CH₃NH₃I was weighed, then thetwo were preferentially mixed in 400 μL of DMSO solution, stirred fullyat 25° C. for about 2 h. When the solution was uniform, 299.36 mg ofPbI₂ powder was weighed, and then 1600 μL of DMF reagent was drawn to beadded in the solution to obtain a mixture, the mixture was continued toheat and stir at 65° C. until it was completely dissolved, and finallycooled to room temperature for use. The mixture was subjected to heatingcoating in the air with a humidity of 20%-80%, the glass substrate wasmaintained smooth and tidy during the entire coating process, and thetemperature was maintained at 25° C.-250° C. First, the glass substratewas heated to 80-100° C., the spin-coating speed was set to 500-1000rpm/min, and the spin-coating time was 5-10 s, secondly, thespin-coating speed was set to 2000-6000 rpm/min, the spin-coating timewas 5-10 s, the substrate was heated continuously between the twospin-coating steps. The film obtained after spin-coating was coveredwith a petri dish with a diameter of 100 mm, and then subjected to aheat treatment at 80-120° C. Finally, a flat and smooth two-dimensionalperovskite pure-phase quantum well film with micron-level grains wasobtained, of which the chemical formula is[CH₃(CH₂)₃NH₃]₂(CH₃NH₃)₃Pb₄I₁₃.

Example 4

Preparation of Two-Dimensional Perovskite Pure-Phase Quantum Well Film(m-Value is 5, a Broad Quantum Well Structure with a Narrow Band-Gap):

34.84 mg of butylamine acetate ionic liquid CH₃(CH₂)₃NH₃ ⁺—CH₂COO⁻ wasdrawn, 124.92 mg of methyl ammonium iodide CH₃NH₃I was weighed, then thetwo were preferentially mixed in 400 μL of DMSO solution, stirred fullyat 25° C. for about 2 h. When the solution was uniform, 295.51 mg ofPbI₂ powder was weighed, and then 1600 μL of DMF reagent was drawn to beadded in the solution to obtain a mixture, the mixture was continued toheat and stir at 65° C. until it was completely dissolved, and finallycooled to room temperature for use. The mixture was subjected to heatingcoating in the air with a humidity of 20%-80%, the glass substrate wasmaintained smooth and tidy during the entire coating process, and thetemperature was maintained at 25° C.-250° C. First, the glass substratewas heated to 80-100° C., the spin-coating speed was set to 500-1000rpm/min, and the spin-coating time was 5-10 s, secondly, thespin-coating speed was set to 2000-6000 rpm/min, the spin-coating timewas 5-10 s, and the substrate was heated continuously between the twospin-coating steps. The film obtained after spin-coating was coveredwith a petri dish with a diameter of 100 mm, and then subjected to aheat treatment at 80-120° C. Finally, a flat and smooth two-dimensionalperovskite pure-phase quantum well film with micron-level grains wasobtained, of which the chemical formula is[CH₃(CH₂)₃NH₃]₂(CH₃NH₃)₄Pb₅I₁₆.

Comparative Example 1

a. The n-butylamine iodide CH₃(CH₂)₃NH₃I, methylamine chloride CH₃NH₃Cl,and lead iodide PbI₂ were dissolved in methylamine acetate in a molarratio of 2:3:4, and stirred at 60° C. for 1 h-24 h to obtain a precursorsolution with a concentration of 200 mg·mL⁻¹; b. The precursor solutionwas preheated to 50° C.-100° C., and then spin-coated for 10 s-60 s on aheating spin-coater at 60° C.-130° C., and the heating was continuedduring the whole spin-coating process, and then gradient annealing wasperformed at 60° C.-100° C. for 3 min-10 min to obtain a mixedmulti-quantum well perovskite film with no fixed chemical formula. Itsmain components include [CH₃(CH₂)₃NH₃]₂(CH₃NH₃)Pb₂I₇,[CH₃(CH₂)₃NH₃]₂(CH₃NH₃)₂Pb₃I₁₀, [CH₃(CH₂)₃NH₃]₂(CH₃NH₃)₃Pb₄I₁₃,[CH₃(CH₂)₃NH₃]₂(CH₃NH₃)₄Pb₅I₁₆ and CH₃NH₃PbI₃.

Comparative Example 2

a. The n-butylamine iodide CH₃(CH₂)₃NH₃I, methylamine chloride CH₃NH₃C1,and lead iodide PbI₂ were dissolved in DMF at the molar ratio of 2:3:4,and stirred at 60° C. for 1 h-24 h to prepare a precursor solution witha concentration of 200 mg·mL⁻¹; b. The precursor solution was preheatedto 50° C.-100° C., and then spin-coated for 10 s-60 s on aroom-temperature spin-coater at 60° C.-130° C., and then gradientannealing was performed at 60° C.-100° C. for 3 min-10 min to obtain amixed multi-quantum well perovskite film with no fixed chemical formula.Its main components include [CH₃(CH₂)₃NH₃]₂(CH₃NH₃)Pb₂I₇,[CH₃(CH₂)₃NH₃]₂(CH₃NH₃)₂Pb₃I₁₀, [CH₃(CH₂)₃NH₃]₂(CH₃NH₃)₃Pb₄I₁₃,[CH₃(CH₂)₃NH₃]₂(CH₃NH₃)₄Pb₅I₁₆ and CH₃NH₃PbI₃.

Comparative Example 3

a. The butylamine acetate ionic liquid CH₃(CH₂)₃NH₃ ⁺·CH₃COO⁻,methylamine chloride CH₃NH₃C1, and lead iodide PbI₂ were dissolved inDMF at the molar ratio of 2:3:4, and stirred at 60° C. for 1 h-24 h toprepare a precursor solution with a concentration of 200 mg·mL⁻¹; b. Theprecursor solution was preheated to 50° C.-100° C., and then spin-coatedfor 10 s-60 s on a room-temperature spin-coater at 60° C.-130° C., andthen gradient annealing was performed at 60° C.-100° C. for 3 min-10 minto obtain a mixed multi-quantum well perovskite film with no fixedchemical formula. The main components include[CH₃(CH₂)₃NH₃]₂(CH₃NH₃)Pb₂I₇, [CH₃(CH₂)₃NH₃]₂(CH₃NH₃)₂Pb₃I₁₀,[CH₃(CH₂)₃NH₃]₂(CH₃NH₃)₃Pb₄I₁₃, [CH₃(CH₂)₃NH₃]₂(CH₃NH₃)₄Pb₅I₁₆ andCH₃NH₃PbI₃.

The two-dimensional perovskite pure-phase quantum well films prepared inExamples 1, 2, 3, 4 and Comparative Examples 1, 2, and 3 were subjectedto ultrafast spectroscopy analysis. The equipment name and testconditions are as follows: ultrafast system HELIOS-TA spectrometer, thelaser source is a Coherent Legend regenerative amplifier (150 fs, 1 KHz,800 nm) injected by a Coherent Vitesse oscillator (100 fs, 80 MHz).Broadband probe pulse (420-780 nm) is generated by focusing a small part(about 10 mj) of a basic 800 nm laser pulse onto a 2 mm sapphire plateto obtain FIG. 2 , FIG. 3 , FIG. 4 , FIG. 5 , FIG. 6 , FIG. 7 and FIG. 8, respectively.

It can be seen from the figures that the two-dimensional perovskitepure-phase quantum well film prepared in Example 1 has a singleperovskite pure-phase quantum well with an n-value of 2, i.e. thedistribution width of the quantum well is two lead-iodine octahedrons onaverage, it is well distributed with no quantum wells with other nvalues, and the purity is close to 100%. According to the scanningelectron micrographs, it can be seen that the grain size of theperovskite film has reached the micron level with a high crystallinity,the film is dense and has no holes, and the surface is smooth and flat.

The two-dimensional perovskite pure-phase quantum well film prepared inExample 2 has a single perovskite pure-phase quantum well with an nvalue of 3, i.e. the distribution width of the quantum well is threelead-iodine octahedrons on average, it is well distributed with noquantum wells with other n values, and the purity is close to 100%.

The two-dimensional perovskite pure-phase quantum well film prepared inExample 3 has a single perovskite pure-phase quantum well with an nvalue of 4, i.e. the distribution width of the quantum well is fourlead-iodine octahedrons on average, it is well distributed with noquantum wells with other n values, and the purity is more than 98%.

The two-dimensional perovskite pure-phase quantum well film prepared inExample 4 has a single perovskite pure-phase quantum well with an nvalue of 5, i.e. the distribution width of the quantum well is fivelead-iodine octahedrons on average, it is well distributed with noquantum wells with other n values, and the purity is more than 98%.

The two-dimensional perovskite multiphase quantum well film prepared inComparative Example 1 has a target quantum well width of 4, but acomplex multiphase quantum well film is actually obtained, whichcontains phases with various widths of 2, 3, 4 and infinitethree-dimensional perovskite parts, and even impurity phases such aslead iodide. It can be seen from the scanning electron micrographs thatthe perovskite film has a smaller grain size in the nanometer range, andthe crystallinity of the grain is average, the film has a small numberof holes and a high surface roughness.

The two-dimensional perovskite multiphase quantum well film prepared inComparative Example 2 has a target quantum well width of 4, but acomplex multiphase quantum well film is actually obtained, whichcontains phases with various widths of 2, 3, 4 and infinitethree-dimensional perovskite parts, even the content of infinity phaseis more, and there are still impurity phases such as lead iodide.

The two-dimensional perovskite multiphase quantum well film prepared inComparative Example 3 has a target quantum well width of 4, but acomplex multiphase quantum well film is actually obtained, whichcontains phases with various widths of 2, 3, 4 and infinitethree-dimensional perovskite parts, even the content of infinity phaseis more, and there is still a small amount of impurity phases such aslead iodide.

It can be seen that the films prepared in Examples 1-3 are significantlybetter than the films prepared in Comparative Examples 1 and 2 in termsof crystallinity, grain size, especially the width distribution andpurity of quantum wells.

The foregoing description of the disclosed embodiments enables thoseskilled in the art to implement or use the present disclosure. Variousmodifications to these embodiments will be obvious to those skilled inthe art, and the general principles defined herein can be implemented inother embodiments without departing from the spirit or scope of thepresent disclosure. Therefore, the present disclosure will not belimited to the embodiments shown in this document, but should conform tothe widest scope consistent with the principles and novel featuresdisclosed in this document.

1. An organic proton-type alkylamine acetate ionic liquid, wherein achemical formula of the organic proton-type alkylamine acetate ionicliquid is RNH₃ ⁺—RCOO⁻, where R represents an alkyl group of C4-8 or aphenyl group.
 2. A method for preparing the organic proton-typealkylamine acetate ionic liquid, and the organic proton-type alkylamineacetate ionic liquid is a butylamine acetate ionic liquid, having achemical formula of H₃(CH₂)₃NH₃ ⁺—CH₂COO⁻, comprising:
 1. mixing acarboxyl group-containing organic acid and an amine group-containingorganic amine in a molar ratio of the amine group and the carboxyl groupof 1:1, then adding a same volume of a first diluent as the aminegroup-containing organic amine, cooling to 0° C. and stirring to reactfor 2-2.5 h to obtain a mixture; and
 2. removing the first diluent andother organic impurities from the mixture by reduced pressuredistillation at 80° C., then lowering the temperature to −4° C. forrecrystallization, standing for 1 hour to obtain a solidified mixture,washing the solidified mixture with 1000 mL of a volatile anti-solventfor 3 times, then dissolving the solidified mixture in 100 mL of asecond diluent, stirring for 30 min, and then removing the seconddiluent by reduced pressure distillation at 80° C. to obtain the organicproton-type alkylamine acetate ionic liquid.
 3. (canceled)
 4. The methodaccording to claim 2, wherein the carboxyl group-containing organic acidcomprises one or more of formic acid, acetic acid, propionic acid,butyric acid, pentanoic acid and hexanoic acid; the aminegroup-containing organic amine is one or more selected fromaminomethane, (di)aminoethane, (di)aminopropane, (di)aminobutane,(di)aminopentane and (di)aminohexane; the first diluent is one or moreselected from water, ethanol, methanol, propanol and isopropanol; andthe volatile anti-solvent is an ethers reagent.
 5. The method accordingto claim 4, wherein the ethers reagent is diethyl ether.
 6. (canceled)7. (canceled)
 8. A two-dimensional perovskite pure-phase quantum wellmaterial prepared based on an organic proton-type alkylamine acetateionic liquid, wherein a chemical formula of the two-dimensionalperovskite pure-phase quantum well material is A_(a)B_(b)M_(m)X_(x),where: A is a long carbon chain organic cation, and a-value ranges from0 to 2.5; B is an amine group-containing monovalent cation, b-valuesatisfies 0≤(m−1)<b<(m+1), and m is any natural number; M is a divalentmetal cation; and X is one or more of halogen ion, carboxylate ion andthiocyanate ion, and x-value satisfies (3m−1)<x<(3m+1).
 9. Thetwo-dimensional perovskite pure-phase quantum well material according toclaim 8, wherein: the long carbon chain organic cation is one or more ofCH₃CH₂NH₃ ⁺, CH₃CH₂CH₂NH₃ ⁺, CH₃CH₃CH₂CH₂NH₃ ⁺, CH₃CH₂CH₂CH₂CH₂NH₃ ⁺ andCH₃CH₂CH₂CH₂CH₂CH₂NH₃ ⁺; the amine group-containing monovalent cation isone or more of methylamine ion, formamidine ion, guanidine ion, andcesium ion; the divalent metal cation is one or more of lead ion, tinion, copper ion, zinc ion, manganese ion and bismuth ion; and thehalogen is one or more of F, Cl, Br, and I.
 10. The two-dimensionalperovskite pure-phase quantum well material according to claim 8,wherein a chemical formula of the two-dimensional perovskite pure-phasequantum well material is A₂B₂M₃X₁₀.
 11. The two-dimensional perovskitepure-phase quantum well material according to claim 8, wherein achemical formula of the two-dimensional perovskite pure-phase quantumwell material is [CH₃(CH₂)₃NH₃]₂(CH₃NH₃)Pb₂I₇,[CH₃(CH₂)₃NH₃]₂(CH₃NH₃)₂Pb₃I₁₀, [CH₃(CH₂)₃NH₃]₂(CH₃NH₃)₃Pb₄I₁₃ or[CH₃(CH₂)₃NH₃]₂(CH₃NH₃)₄Pb₅I₁₆.
 12. A method for preparing a film with atwo-dimensional perovskite pure-phase quantum well structure,comprising:
 1. preparing materials in a molar ratio of the organicproton-type alkylamine acetate ionic liquid according to claim 1, BX andMX of 2:(m+1):m;
 2. adding BX to a DMSO solution to prepare a DMSOmixture with a BX mass fraction of 1-35%;
 3. adding the organicproton-type alkylamine acetate ionic liquid to the DMSO mixture preparedin step 2), mixing evenly, stirring at 25° C. for 2 h, and then addingMX;
 4. then adding 1600 μL of a DMF reagent, heating to 65° C. andstirring until fully dissolved, and cooling to room temperature toobtain a mixed solution; and
 5. subjecting the mixed solution preparedin step 4) to spin-coating with heating on the surface of a glasssubstrate in the air with a humidity of 20%-80%, and maintaining thetemperature at 25° C.-250° C. to obtain the two-dimensional perovskitepure-phase quantum well film; wherein, X is one or more of halogen ion,carboxylate ion and thiocyanate ion; BX is a compound salt of amonovalent cation; and MX is a compound formed by a divalent metalcation and an X ion.
 13. The method according to claim 12, wherein thecompound salt of the monovalent cation is one or more selected from acompound salt of methylamine ion, a compound salt of formamidine ion, acompound salt of guanidine ion and a compound salt of cesium ion. 14.The method according to claim 12, wherein an addition amount of the DMFreagent in step 3) is 5-50 times an addition amount of the organicproton-type alkylamine acetate ionic liquid in volume.
 15. The methodaccording to claim 12, wherein the spin-coating with heating comprises:heating the glass substrate to 80° C.-100° C., setting a spin-coatingspeed to 500-1000 rpm/min and performing spin-coating for 5-10 s, thensetting a spin-coating speed to 2000-6000 rpm/min and performingspin-coating for 5-10 s, continuously heating the substrate between thetwo spin-coating steps, covering a film obtained after spin-coating witha petri dish with a diameter of 100 mm, and then subjecting toheat-treatment at 80° C.-120° C. for 5-10 min.
 16. The method accordingto claim 12, comprising:
 1. preparing materials in a molar ratio of abutylamine acetate ionic liquid, methyl ammonium iodide and lead iodideof 2:4:3;
 2. adding methyl ammonium iodide to a DMSO solution to preparea DMSO mixture with a mass fraction of methyl ammonium iodide of 1-35 wt%;
 3. adding the butylamine acetate ionic liquid to the DMSO mixtureprepared in step 2), mixing evenly, stirring at 25° C. for 2 h, and thenadding lead iodide powder; then adding a DMF reagent, heating to 65° C.,stirring until fully dissolved, and cooling to room temperature toobtain a mixed solution; and
 4. subjecting the mixed solution preparedin step 3) to spin-coating with heating on the surface of a glasssubstrate in the air with a humidity of 20%-80%, and maintaining thetemperature at 25° C.-250° C.
 17. The two-dimensional perovskitepure-phase quantum well material according to claim 11, wherein: thelong carbon chain organic cation is one or more of CH₃CH₂NH₃ ⁺,CH₃CH₂CH₂NH₃ ⁺, CH₃CH₃CH₂CH₂NH₃ ⁺, CH₃CH₂CH₂CH₂CH₂NH₃ ⁺ andCH₃CH₂CH₂CH₂CH₂CH₂NH₃ ⁺; the amine group-containing monovalent cation isone or more of methylamine ion, formamidine ion, guanidine ion, andcesium ion; the divalent metal cation is one or more of lead ion, tinion, copper ion, zinc ion, manganese ion and bismuth ion; and thehalogen is one or more of F, Cl, Br, and I.
 18. The method according toclaim 12, wherein the ionic liquid is a butylamine acetate ionic liquid,and a chemical formula of the butylamine acetate ionic liquid isCH₃(CH₂)₃NH₃ ⁺—CH₂COO⁻.